AISI 8645 Steel Rod/Bar

AISI 8645 Steel Rod Product Information -:- For detailed product information, please contact sales. -: AISI 8645 Steel Rod Synonyms -:- For detailed product information, please contact sales. -:

AISI 8645 Steel Product Information -:- For detailed product information, please contact sales. -: # **Technical Data Sheet: AISI 8645 Alloy Steel** ## **Nickel-Chromium-Molybdenum Medium-Carbon Alloy Steel** --- ### **1. Material Overview** **Designation:** AISI 8645 / UNS G86450 **Material Classification:** Nickel-Chromium-Molybdenum (Ni-Cr-Mo) Medium-Carbon Alloy Steel **Key Characteristics:** AISI 8645 is a versatile medium-carbon alloy steel within the 86xx series, distinguished by its carbon content range of 0.43-0.48%. This composition provides enhanced hardenability and strength potential compared to the lower-carbon 8640 grade, while maintaining good toughness and fatigue resistance. The balanced alloying of nickel, chromium, and molybdenum ensures reliable through-hardening characteristics, making it suitable for moderately sized components requiring higher strength and wear resistance than provided by 8640. --- ### **2. International Standards Compliance** **Primary Specifications:** - **UNS:** G86450 - **ASTM Standards:** - **A322:** Standard Specification for Steel Bars, Alloy, Standard Grades - **A331:** Alloy Steel Bars Subject to Mechanical Property Requirements - **A519:** Seamless Carbon and Alloy Steel Mechanical Tubing - **SAE/AISI:** - SAE J404: Chemical Compositions of SAE Alloy Steels - SAE J412: Alloy Steel Bars - **ISO Standards:** - **ISO 683-11:** Heat-treatable steels, alloy steels and free-cutting steels - **European Standards:** - **EN 10083-3:** Steels for quenching and tempering - **1.6546** (34CrNiMo6): Similar but with adjusted carbon range - **Japanese Standards:** - **JIS G4105:** Chromium molybdenum steels (SCM440 similar) - **German Standards:** - **DIN 17200:** Case-hardening and heat-treatable steels --- ### **3. Chemical Composition** **Standard Composition Ranges (Weight %):** | Element | Standard Range | Typical Value | Metallurgical Function | |---------|---------------|---------------|------------------------| | **Carbon (C)** | 0.43 - 0.48% | 0.45% | Primary strength element, provides hardenability and wear resistance | | **Manganese (Mn)** | 0.75 - 1.00% | 0.85% | Enhances hardenability, improves strength and hardenability | | **Silicon (Si)** | 0.15 - 0.30% | 0.25% | Deoxidizer, improves strength through solid solution strengthening | | **Nickel (Ni)** | 0.40 - 0.70% | 0.55% | Improves toughness, enhances hardenability and impact resistance | | **Chromium (Cr)** | 0.40 - 0.60% | 0.50% | Increases hardenability depth, improves wear and corrosion resistance | | **Molybdenum (Mo)** | 0.15 - 0.25% | 0.20% | Enhances hardenability, reduces temper embrittlement, improves high-temperature strength | | **Phosphorus (P)** | ≤ 0.035% | 0.020% | Residual element (minimized for improved toughness) | | **Sulfur (S)** | ≤ 0.040% | 0.025% | Residual element (may be increased for improved machinability variants) | | **Iron (Fe)** | Balance | Balance | Matrix element | **Composition Notes:** - Higher carbon content than 8640 (0.38-0.43%) provides increased strength potential - Nickel content improves toughness despite higher carbon level - Molybdenum content critical for controlling grain growth and temper embrittlement - Balanced alloying provides good hardenability without excessive alloy cost **H-Grade Variant (8645H):** - Available with controlled hardenability per SAE J1268 - Tighter composition control for predictable heat treatment response - Guaranteed Jominy hardenability bands for consistent manufacturing --- ### **4. Heat Treatment Characteristics** **Typical Heat Treatment Cycles:** **1. Annealing (for Machining):** - Temperature: 815-845°C (1500-1550°F) - Soak time: 2 hours per inch of thickness - Cooling: Furnace cool to 595°C (1100°F), then air cool - Resulting hardness: 187-229 HB (typically ~207 HB) **2. Normalizing:** - Temperature: 870-900°C (1600-1650°F) - Soak time: 1 hour per inch minimum - Cooling: Air cool - Purpose: Refine grain structure after forging **3. Hardening (Typical):** - Austenitizing: 830-855°C (1525-1575°F) - Quenching: Oil (preferred) or water for smaller sections - Recommended quench severity: H-value 0.35-0.50 (oil) **4. Tempering (Typical Ranges):** - **Low Temperature (205-315°C / 400-600°F):** High hardness (45-55 HRC), high strength, limited toughness - **Medium Temperature (425-540°C / 800-1000°F):** Balanced properties (30-45 HRC), good strength-toughness combination - **High Temperature (595-650°C / 1100-1200°F):** High toughness (24-32 HRC), good impact resistance **Transformation Temperatures:** - **Ac1:** ~725°C (1337°F) - **Ac3:** ~770°C (1418°F) - **Ms:** ~315°C (599°F) - lower than 8640 due to higher carbon - **Mf:** ~150°C (302°F) **Hardenability Characteristics:** - Good through-hardening capability to approximately 50 mm (2") diameter - DI (Ideal Diameter) approximately 70-90 mm (2.8-3.5") in oil - Jominy curve shows good hardenability due to Ni-Cr-Mo combination --- ### **5. Mechanical Properties (Typical)** **Properties After Oil Quenching and Tempering:** | Tempering Temperature | Tensile Strength | Yield Strength (0.2%) | Elongation (%) | Reduction of Area (%) | Hardness | Charpy Impact (20°C) | |----------------------|-----------------|----------------------|----------------|----------------------|----------|---------------------| | **205°C (400°F)** | 1550-1725 MPa | 1240-1380 MPa | 8-12% | 25-35% | 47-52 HRC | 10-20 J | | **425°C (800°F)** | 1240-1380 MPa | 1100-1240 MPa | 10-14% | 35-45% | 38-43 HRC | 20-35 J | | **540°C (1000°F)** | 965-1100 MPa | 830-965 MPa | 12-16% | 40-50% | 30-35 HRC | 30-45 J | | **595°C (1100°F)** | 860-965 MPa | 690-830 MPa | 14-18% | 45-55% | 26-30 HRC | 45-60 J | | **650°C (1200°F)** | 760-860 MPa | 620-760 MPa | 16-20% | 50-60% | 22-26 HRC | 60-80 J | **Property Characteristics by Section Size (540°C temper example):** | Diameter | Surface Hardness | Core Hardness | Tensile Strength | Yield Strength | |----------|-----------------|---------------|-----------------|----------------| | **25 mm (1")** | 32-36 HRC | 32-36 HRC | 1035-1105 MPa | 895-965 MPa | | **50 mm (2")** | 31-35 HRC | 30-34 HRC | 965-1035 MPa | 860-930 MPa | | **75 mm (3")** | 29-33 HRC | 28-32 HRC | 895-965 MPa | 795-860 MPa | | **100 mm (4")** | 27-31 HRC | 25-29 HRC | 825-895 MPa | 725-795 MPa | **Physical Properties:** | Property | Value | Units | Conditions | |----------|-------|-------|------------| | **Density** | 7.85 | g/cm³ | At 20°C | | **Melting Range** | 1415-1460 | °C | - | | **Thermal Conductivity** | 41.5 | W/m·K | At 100°C | | **Specific Heat Capacity** | 460 | J/kg·K | At 100°C | | **Coefficient of Thermal Expansion** | 11.5 × 10⁻⁶ | /°C | 20-100°C | | **Modulus of Elasticity** | 205 | GPa | At 20°C | | **Shear Modulus** | 80 | GPa | At 20°C | | **Poisson's Ratio** | 0.29 | - | - | | **Electrical Resistivity** | 0.23 | μΩ·m | At 20°C | **Fatigue Properties (Rotating Beam, R=-1):** - Endurance limit: ~50% of tensile strength - Notch sensitivity: Moderate to high (use proper design) - Surface finish critical for fatigue performance --- ### **6. Material Characteristics & Performance** **Key Advantages:** 1. **Enhanced Strength:** Higher carbon content provides greater strength than 8640 2. **Good Hardenability:** Through-hardening possible to moderate diameters 3. **Balanced Toughness:** Maintains reasonable impact resistance despite higher carbon 4. **Wear Resistance:** Superior to lower-carbon grades at equivalent hardness 5. **Fatigue Strength:** Good fatigue resistance for dynamically loaded components 6. **Cost-Effective:** Provides strength increase without moving to premium alloys **Performance Limitations:** 1. **Toughness vs. 8640:** Lower impact resistance than AISI 8640 at same tempering conditions 2. **Weldability:** More challenging than lower-carbon steels 3. **Maximum Section Size:** Limited to ~75 mm for consistent through-hardening 4. **Machinability:** Lower than annealed 8640 due to higher hardness potential **Special Characteristics:** - Responds well to surface hardening processes (induction, flame) - Suitable for carburizing applications when case hardness >60 HRC required - Good dimensional stability during heat treatment with proper processing - Moderate susceptibility to temper embrittlement (375-575°C range) --- ### **7. Manufacturing & Processing** **Machinability:** - **Annealed Condition:** 55-60% of B1112 steel - **Hardened Condition:** Requires carbide tools, reduced speeds - **Recommended Tools:** Coated carbide for production, HSS for toolroom - **Cutting Parameters:** 60-90 m/min turning, lower for milling and drilling - **Coolant:** Essential for heat management and chip control **Forming & Forging:** - **Hot Working:** 1150-900°C (2100-1650°F) - **Cold Working:** Limited due to high strength; intermediate annealing required - **Forging:** Excellent forgeability in proper temperature range - **Annealing Required:** After cold working or between forging operations **Heat Treatment Considerations:** - **Preheating:** Recommended for sections >25 mm to minimize distortion - **Quenching Medium:** Oil preferred; water for simple shapes and small sections - **Tempering:** Immediate tempering after quenching to prevent cracking - **Stress Relieving:** Beneficial for complex geometries **Welding (Not Generally Recommended):** - **If Required:** Preheat 200-300°C, use low-hydrogen electrodes - **Post-Weld:** Temper immediately at 595-650°C - **Filler Metals:** AWS A5.28 ER80S-B2 or similar - **Considerations:** Anneal before welding if possible, re-heat treat after --- ### **8. Applications** **Automotive & Transportation:** - Heavy-duty axle shafts for trucks and buses - Transmission gears and shafts requiring higher strength - Large engine crankshafts and connecting rods - Heavy vehicle steering components - Off-highway vehicle drive train parts **Industrial Machinery:** - Gearbox shafts and pinions for heavy equipment - Large pump shafts and impellers - Compressor crankshafts and components - Machine tool spindles and arbors - Heavy-duty bearing races and journals **Construction & Mining Equipment:** - Excavator bucket pins and bushings - Crane sheave shafts and pins - Mining equipment drive components - Drill rod couplings and adapters - Heavy-duty fasteners and bolts **Oil & Gas Industry:** - Drill string tool joints - Pump shafts for mud and injection pumps - Valve stems for high-pressure service - Wellhead equipment components - Downhole tool bodies **Agricultural Equipment:** - Tractor transmission gears - Combine harvester drive shafts - Large implement components - PTO shafts for heavy-duty applications - Plow and tillage components **General Manufacturing:** - Large dies and molds - Press tooling components - Rolling mill rolls (smaller diameters) - Special machinery shafts - High-strength fasteners **Comparison with Similar Grades:** - **vs. 8640:** Higher strength, better wear resistance, slightly lower toughness - **vs. 4340:** Lower cost, adequate for many applications, lower hardenability - **vs. 4140:** Better toughness, higher alloy cost, better hardenability - **vs. 8740:** Similar strength, different alloy balance --- ### **9. Quality Assurance & Testing** **Standard Testing:** - Chemical analysis (spectrographic or combustion) - Tensile testing per ASTM A370 - Impact testing (Charpy V-notch) - Hardness testing (Rockwell or Brinell) - Microstructural examination (grain size, inclusion rating) **Enhanced Testing (as specified):** - Non-destructive testing (UT, MPI, dye penetrant) - Fatigue testing - Fracture toughness testing - Hydrogen content analysis - Residual stress measurement **Certification Requirements:** - Mill Test Certificate per EN 10204 3.1 or 3.2 - Chemical composition certificate - Mechanical test reports - Heat treatment records (if supplied heat treated) - Traceability documentation --- ### **10. Comparative Analysis** **Within 86xx Series:** - **8640:** Lower strength (1035 MPa vs 1100 MPa at 540°C temper), better toughness - **8642:** Intermediate properties, good compromise - **8645:** Highest strength in series, maximum wear resistance - **8650:** Similar to 8645 with slightly different hardenability **vs. Other Alloy Steels:** - **4140:** Lower cost, lower toughness, adequate for many applications - **4340:** Higher strength potential, better toughness, higher cost - **5140:** Lower hardenability, lower cost, chromium only - **6150:** Higher wear resistance, spring applications **Selection Guidelines:** - Choose 8645 when higher strength than 8640 is required - Consider 4340 for larger sections or higher toughness requirements - Use 4140 for cost-sensitive applications with moderate requirements - Select based on specific strength, toughness, and hardenability needs --- ### **11. Technical Recommendations** **Design Considerations:** - Maximum recommended diameter: 75 mm for through-hardening - Use generous fillet radii to minimize stress concentrations - Consider shot peening for improved fatigue life - Design for compressive loading where possible **Heat Treatment Recommendations:** - Oil quench for most applications - Immediate tempering after quenching - Consider double tempering for maximum toughness - Use controlled atmosphere to minimize decarburization **Procurement Specifications:** ```plaintext MATERIAL: AISI 8645 Alloy Steel FORM: Round Bar, Square Bar, Flat Bar, or Forging Stock CONDITION: Annealed, normalized, or heat treated as specified SPECIFICATION: ASTM A322 Grade 8645 CHEMISTRY: Per AISI 8645 requirements TESTING: As per ASTM A370 CERTIFICATION: EN 10204 3.1 minimum ``` **Safety Factors (Typical):** - Static loading: 2.0-2.5 - Fatigue loading: 1.8-2.2 - Impact loading: 3.0-4.0 - Combined loading: 2.5-3.0 --- ### **12. Economic Considerations** **Cost Factors:** - Material cost: Moderate among alloy steels - Processing cost: Standard heat treatment required - Machining cost: Higher than low-carbon steels - Life cycle cost: Favorable for demanding applications **Value Proposition:** - Provides strength increase over 8640 without premium alloy cost - Good balance of properties for many engineering applications - Proven reliability in demanding service - Available from multiple sources --- ### **13. Environmental & Sustainability** **Environmental Impact:** - Fully recyclable at end of life - Moderate energy requirement for production - Standard steel manufacturing processes - Compliant with RoHS and REACH regulations **Sustainability Considerations:** - Long service life reduces replacement frequency - High strength allows weight reduction in designs - Compatible with green manufacturing initiatives - Established recycling infrastructure --- **Disclaimer:** This technical data sheet provides general information about AISI 8645 alloy steel. Properties are typical and may vary based on specific manufacturing processes, heat treatment parameters, and section size. For critical applications, conduct appropriate testing and consult with materials engineering professionals. The information presented does not constitute a warranty or specification. --- **Document Control** - **Document:** TDS-8645-GEN - **Revision:** 1.0 - **Date:** March 2024 - **Prepared By:** Materials Engineering Department - **Approved By:** Technical Manager - **Quality System:** ISO 9001:2015 Certified -:- For detailed product information, please contact sales. -: AISI 8645 Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6361 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: AISI 8645 Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 8645 Steel Rod -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 8645 Steel Rod -:- For detailed product information, please contact sales. -:

Packing of AISI 8645 Steel Rod -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and Steel Rod drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 2832 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition